The Problems With Wisteria Vines

by Hallie Engel

Wisteria can grow to over 25 feet in height and has fragrant blossoms.

Wisteria (Wisteria spp.) is a genus of 10 different climbing vines and a member of the pea family. Covered in flowers and able to climb high, wisteria are vigorous vines best for U.S. Department of Agriculture plant hardiness zones 4 through 9. Growing wisteria is not without challenges, though, and gardeners may face various difficulties with this beguiling vine.

Scales

Two species of scales, tiny insects with hard shells, attack wisteria vines. The calico scale is a type of soft scale with a light brown covering. As it feeds on wisteria, calico scales secrete honeydew, a sugary substance that causes disease and attracts ants. Wisteria scales are darker in color and also feed by attaching themselves to the vines. To protect against both types of scales, spray wisteria with horticultural oil or introduce natural predators, such as lacewings or parasitic wasps.

Flower Troubles

Wisteria vines are prized for their colorful flowers, but getting them to bloom can be hard for various reasons. Some wisteria plants take 20 years to bear flowers, so purchase a mature plant that has blossomed already to avoid disappointment. From July to September, give wisteria extra water during dry spells, because this is when its flower buds develop for the following season. Avoid growing wisteria vines in shady spots, as they need full sun to flower.

Graft Failure

When wisteria is propagated by grafting, in which the vascular tissues of two plants are fused together, graft failure may occur. There are many causes of graft failure, including plant healing affected by extreme temperatures or improper sanitation, leading to disease. When graft failure takes place, the plant can no longer provide its top growth with nutrients. To avoid this problem, choose healthy wisteria vines for planting, and inspect their graft union, which should be calloused and free of damage and suckers.

Diseases

Wisteria vines should be inspected regularly for signs of certain diseases. Canker diseases leave wisteria covered in dark lesions and destroy foliage as the plant dies. Keep wisteria hardy to prevent canker problems, and prune infected parts of the vines immediately. Tobacco mosaic virus also affects wisteria and causes a mottled discoloration on foliage as it progresses. There is no cure for the virus, which is easily spread. Purchase resistant types of wisteria, and remove and destroy infected vines immediately.

About the Author

Hallie Engel is a food and lifestyle writer whose work has appeared in several international publications. She served as a restaurant critic for "Time Out Abu Dhabi" and "Time Out Amsterdam" and has also written about food culture in the United Arab Emirates for "M Magazine." She holds a bachelor's degree in communications and film studies from University of Amsterdam.

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